Invitation letter for self-funded UK standard visa application

I’m going to apply for a UK standard tourist visa along with my wife and kid. I have enough savings to fund my 10-days visit. I'm planning to attach an invitation letter from a friend residing in the UK, and we'll be staying at his house. He'll accommodate us but all other expenses I'll take care of myself.
So, besides the invitation letter, what other documents should he send me for my tourist visa application? Is it a good idea to attach an invitation letter from a not-so-close friend? Does he need to attach his financial statements to invite me when I have enough funds to support our trip?
Pictures about "Invitation letter for self-funded UK standard visa application"



How do I write a letter of invitation for UK visa?
If you do not know where to start writing a letter of invitation for a UK visa, write the following information in a list:Do you need invitation letter for UK visa?
To apply for the UK visit visa it is required that the applicant submits an invitation letter.How do I write a letter of invitation visa?
How to Write a Letter of Invitation for US Visa?Do you need a letter of invitation for your visa application?
An invitation letter for Australia is not obligatory for all of the visas. It's usually required for Australian temporary visit tourist visas, and even then it might not be a strict requirement. However, having an invitation letter will increase the chances of receiving a visa.How to Write a Cover Letter For Standard Visitor Visa UK
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Tara Winstead, Olya Kobruseva, Dominika Roseclay, RODNAE Productions